Vulcanizable composition of matter having comminuted leather as a base and method of preparing same.



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VUIJCANIZABLE CQMEOSITION 01" MATTE R HAVIITG- COMMINUTED LEATHER AS Anear.

AND METHOD OF PREPARING- SAME.

il,32,4l63.

I\To Drawing.

To all whom it may concern:

Be it known that I, Join: STUART CAMB- BELL, a subject of the King ofGreat Britain and Ireland, residing at Room 35, Broad Street House, NewBroad Street, London, E. 2, England, have invented a new and usefulvulcanizable Composition of Matter Having Comminuted Leather as a Baseand Methods of Preparing Same, of which the following is aspecification.

This invention consists in a new and useful rulcanizable composition ofmatter and a method of preparing same, the said com position containingcomminuted or disintegrated leather as a" base. and being suitable inits vulcanized state for most of the purposes for which leather, indiarubber or the like are used, besides being capable of being reduced to asemi-fluid state before it is vulcanized so that it can be applied on acanvas or other backing and then Vulcanized. The comminuted leather ispreferably obtained by grinding or disintegrating waste or scrapleather.

Many compositions are known which contain comminuted or disintegratedleather as a base together with fibrous material, filling material, oilsor fats, and'rubber or some other binding. agent, and as compared withsuch compositions the characteristic feature of the present inventionconsists in that the comminuted or disintegrated leather is subjected topreliminary treatment for the purpose of eliminating entirely the fattymatter naturally in the leather.

The essential ingredients of the new com.- position are disintegrated orcomminuted leather which has been boiled in water containing suflicientcaustic alkali to saponify the fatty matter in the leather, and avulcanizable gum such as rubber, caoutchouc, ba

lata or like resilient and vulcanizable binding material. Any desiredfilling material and any required coloring and preserving agents may beadded. The vulcanizing agent may be introduced at any stage. Thepreferred filling materials are magnesia or asbestos fiber or asbestosdust (about 15% of the weight of the comminuted leather if a productresembling leather be required) fibrous material such as hair or wool oranimal or vegetable fiber, chalk or whitening, (about 5%) and lime,(about 2%). The proportions of the resilient vulcanizable bindingmaterial will Vary with Specification of Letters Patent. Patented Apr.29)., 19119. Application filed September 17, 1917. Serial No. 191,750.

the degree of elasticity required in" the fin- 1Sll6d product-about 15%of the weight of the comminuted leather yielding a product resemblingleather.

The preferred method of preparing the said composition consists firstlyin boiling the leather, after it has been ground to owder, in watercontaining sufiicient caustlc alkali to saponifythe fatty matternaturally in the leather, until the leather has been converted into ajelly-like mass-which will usually occur in about an hour and a half.The filling material and, if desired, the sulfur or other vulcanizingagent and any required coloring and preserving agents, may then be addedand thoroughly mixed with the jelly-like mass, in which case the boilingis continued. until the ingredients are thoroughly incorporated witheach other. It is not essential however to make these additions at thisstage; they may be made during the subsequent mixing stage. lln eithercase, the mass after boiling'is dried, for example in vacuum pans ortrays, until it crumbles readily to powder.

In the mixing stage, the elastic gum or rubber or like resilient andvulcanizable binding material is introduced between heated mixingrollers and the dried mass obtained as hereinbefore described isincorporated with it. If the filling material and other ingredients havenot been added during the boiling stage they are now added together withthe sulfur or other vulcanizing agent.

The product is then calendered into sheets of the desired thickness ormolded into, the desired shape or form and vulcanized; or, if sheets orhands capable of withstanding considerable tension are required, thesaid product is rendered more or less fluid by means of a suitablesolvent and applied upon a backing, vulcanized.

During the mixing and rolling operation, steel or metal dust may. beadded for the such as canvas, and afterward purpose of rendering theresultant product When the composition is to be applied upon a canvas orlike backing for thepurpose of making belts, tire-covers, llnlngs,waterproof sheets or the like 1t may be rendcrcd semi-fluid by means ofa solvent such as naphtha.

By suitably regulating the proportions of the ingredients and the degreeof vulcanization a material suitable for electrical insulation isproduced. The hardness of the matcrial may be varied to suitrequirements, and is largely dependent upon the amount of the sulfur orother vulcanizing agent and the temperature and time of vulcanization.

What I claim as my invention and desire to secure by Letters Patent is:

1. A vulcanizable composition having comminutcd or disintegrated leatheras a base, the essential constituents of which are comminuted ordisintegrated leather which has been boiled in water containingsuflicient caustic alkali to saponify the fatty matter in the leather,but not sufficient to dissolve the leather, and a resilient vulcanizablebinding material, the said constituent-s being thoroughly mixed andincorporated with each other, under the action of heat to form ahomogeneous mass.

A vulcanizable composition consisting of comminuted or disintegratedleather which has been boiled in Water containing sufficient causticalkali to saponify the fatty matter in the leather, but not suflicientto dissolve the leather, magnesia, whitening, lime and a resilientvulcamzable binding material, incorporated with each other and withvulcan izing, coloring and preserving agents, under the action of heatto form a homogeneous mass substantially as set forth.

A method of preparing the composition claimed in claim 1, consisting ingrinding scrap leather to powder and boiling same in water containingsuificient caustic alkali to saponify the fatty matter in the leather,but not sufficient to dissolve the leather, then drying and thoroughlymixing and incorporating the powder thus treated with a resilientvulcanizable binding material, under the action of heated mixingrollers.

l. The mode herein described of improv ing the quality of vulcanizablecompounds of comminuted leather and rubber, the said mode consisting inboiling the comminuted leather in Water containing sufiicient caus- -ticalkali to saponify the fatty matter in the leather, but not sufficientto dissolve the leather and then incorporating same with the rubber.

In testimony whereof I have signed my name to this specification.

JOHN STUART CAMPBELL.

